Go Direct® pH Sensor (GDX-PH)
Specifications and User Guide

– Primary Test: It should read approximately 4 in its storage solution.

– Secondary Test: Take readings in fresh buffers, NOT distilled water! The pH reading should be within 0.2 pH units of the pH buffer. For example, if using a pH 4.0 buffer, your reading should be between 3.8 and 4.2.
If no buffers are available, try it in vinegar (~ pH 2.5-3.5) and ammonia (~ pH 10.5-11.5). If readings do not change when the sensor is placed in different solutions, the sensor is possibly defective or damaged.

Which pH Sensor Should I Buy?
Blog post: Answers to your top five pH questions


Go Direct pH sensor calibration in Graphical Analysis software

Why won't my pH Sensor calibrate?
Where do I get pH buffer solutions?
What is the difference between the pH buffer capsules with order codes PHB and PH-BUFCAP?
How do I change the displayed measurement channel on my Go Direct Electrode Amplifier or ISE Amplifier?

My Go Direct pH arrived in two pieces, how do I put it together?
The glass bulb of my pH Sensor is broken. Can it be repaired?
The pH electrode I have been using no longer seems to work or is slow to respond. Is there anything I can do to fix it?
My pH probe does not give an accurate reading. What should I do?
Why doesn't my pH Sensor read pH 7 in distilled or deionized water?
What type of liquids cause problems for the pH Sensor?

Where do I get pH or ORP Storage Solution? (Buffer Storage Solution)
What do I do about mold growth in my bottle of pH electrode storage solution?
How can I keep my pH or ORP storage solution from spilling when the sensor is in use?
My pH sensors were stored dry. Will they still work?
What is the best way to clean the glass bulb of the pH electrode?
Do any of your sensors require special storage?
I bought your pH buffer capsules. Can I make storage solution for my pH Sensors with this kit?
How do I dispose of my pH sensor?

If the sensor can be turned on when connected by USB but not when disconnected from USB, the battery either needs charging or has reached its end of life and can no longer hold a charge. First, try charging the sensor for several hours. If the sensor still won’t turn on when disconnected from USB, the battery has likely reached its end of life. If you intend to use this sensor wirelessly, the battery will need to be replaced. The rechargeable battery in this sensor is covered by a one year warranty but should last two to five years in typical use.
How do I replace the battery in a Go Direct Wand-Type Sensor?

– for buffers pH 4, 7, 10, pH Buffer Capsule Kit
pH storage solution (500 mL bottle)
replacement pH storage solution bottles (5 bottles)